Columns Retired Columns & Blogs |
Loudspeakers Amplification | Digital Sources Analog Sources Featured | Accessories Music |
Columns Retired Columns & Blogs |
Loudspeakers Amplification Digital Sources | Analog Sources Accessories Featured | Music Columns Retired Columns | Show Reports | Features Latest News Community | Resources Subscriptions |
If the crackling seems centered, that means it's the same in both channels, which would indicate DAC or CD transport, most likely. Few amplifiers have much common circuitry that would result in such problems, and most of those problems would have other nasty manifestation.
Are the power supplies on those components dual mono or shared between channels? If the later you may have a capacitor in one of your power supplies about to die. Just a guess though. You may also have a problem with a decoder chip that's shared between channels. Impossible to diagnose at a distance though.
Process of elimination is the only way to begin. Cold solder joints are still my fallback for crackling noises but you have to find which component is at the source of the noise. If it were in the amp and tube based it would have to be a tube common to both channels, say, a pre amp input tube. This seems unlikely as PL is using a dual triode, no? Not much chance of both sections of the tube failing at the same time. A solid state rectifier possibly, but not the most likely. Power supplies are common to both channels in most gear, so that would be where you being to look once you've settled on a single component as the culprit. You might check whether the amplifier's tubes are still glowing when the sound disappears. Just for the sake of elimination, pull your interconnect cables from all the units and reseat them, the problem could be a bad solder joint in a cable connector.
If it is the PL at the heart of the problem, it should make noise when no signal is applied but with the volume set to an average listening level. If that's not the case here, then the amplifier is likely not your problem. What is? Don't know, could be a switch or a cap in a muting circuit. Eliminate the DAC and go from there. If it isn't the DAC and it isn't the amp, that only seems to leave one other choice if the cables have passed their test. But where in that one other choice might the noise be coming from? That's more than likely a job for a technician with the proper tools to troubleshoot. The best you can do is deliver the troublesome unit to the shop to cut down on time spent at $65 an hour.
Use the Rotel just as a CD player alone to see if you have the noise. Unhook the Rotel digital input to the Benchmark DAC, but keep it connected to the amplifier. See if the noise is still there. If you can borrow a friends CD player with a digital out feature, you should solve the problem. Play the CD directly into the amplifier. If the noise is gone, then either your transport or DAC is bad. Now connect the digital out to the Benchmark DAC. Connect the Benchmark to the amplifier. If the noise is gone, you have Rotel CD transport problem. If the noise is still there, get the Benchmark fixed. These should confirm the problem, I would think.
Mike
An update...I left off one 'component'...I also am using an ancient (15 year old) Audio Alchemy powered digital cable.
I removed the DAC and cable from the setup and have not had the noise reappear (1 hour test). I reinstall the DAC but with another Audio Alchemy cable, and I have not had the problem recur (in the hour I have had to play with it) but the right channel does have a very faint buzz (cannot be heard more than a foot from the speaker).
My next step will be to replace the Audio Alchemy with a basic digital cable and see it the problem goes away.
Off to a record sale...Hope to get back at trouble shooting later today
Reverse the direction of those interconnects between the buzzing component. One set a a time.
I changed out the digital interconnect with no success so I removed the outboard DAC completely...The cut outs persisted so, I figure the problem is the CD player...
So, I need to find a replacement to use as a transport...
Blast...a tube would cost a LOT less. The Rotel is way out of warranty.
Buy an Oppo.
Seems like overkill...all I need is a transport.
My local audio outlet is selling a used Theta data basic transport. Aside from it being older than dirt, and assuming it still works OK, is this a good choice for a transport.
I do know that the Theta Data Basic II transport had a slight edge over the more pricey Theta Jade transport that listed for $2495 back in 1999.
I also had a friend that owned an audio store in Nashville, TN that swore the Theta basic II was on par with the Classe CDT 1 transport that was contemporary with the Theta basic II. And of course the build quality is top shelf. He described the Theta as 'punchy' with no other unwanted electronic inflections.
So, I would say, go for it.
hope this helps.
Got it for review...so far sounds good, at least as good as the old Rotel..I do need a short length of decent digital cable.
Thanks everyone for the advice...
JIMV, what's the expected lifetime of the laser in that baby?
I'm just wondering how long it would be expected to live.
Easily repairable/replaceable?
I have an Adcom CD player from 1995 that was used at least 20 hours a week for 12 years without any sing of failure...if it had a digital out I would be using it as a transport...
That said, I have no idea what the life expectancy is of a laser...no moving parts???
Jim,
I have a balanced 0.5m Acoustic Zen Mc2 digital cable if your interested. 110 ohm.
Thanks,
Mark
I thought digital cables were 75 ohm..?? What does balanced in your description mean...I thought they had a different termination but the photo I looked at for the cable shows standard RCA, which is what I use.
What are you asking for it?
Shows you how much I know about digital cables..been years since I bought one.
There are two digital interfaces that show up on consumer equipment, "SPDIF" which is single-ended 72 ohm, and AES/EBU which is 110 ohm balanced.
Edited to correct impedence due to brain failure...
"short" length of digital cable?
I've read that one of the most important things in a digital cable is length. It should be no less than 5 feet long.(1.5 meters) This reduces the instance of early reflections which is a main factor in sound degradation.
You might want to research that to see how substantiated that is.
Perhaps JJ could comment.
Balanced cable (AES/EBU) 110 ohm, is the industry standard for professional recording studios world-wide. Balanced cable has the same equal impedence from one end to another thus using very long runs of cable are not an issue. Unbalanced (RCA)75 ohm digital cables have unequal impedences and long runs could be an issue. Thats about all I know.
Sonically, I can hear no differences between the two. Both sound great.
The cable cost $300 new. Im selling mine for $100. Even though my cable is an older version, it is practically new and in great condition. The cable looks like this one but with black Neutrik connectors and is a little darker gray in color than this one.
I think I am better off with a setup with RCA termination..Thanks for the offer though. Too close to Christmas for another purchase...
For my own info...As I understand it, the Theta has a balanced out, the benchmark has balanced BUT the amp does not have a balanced in. I need to run balanced to the DAC and then to the amp do I not?? That would involve more cables and an amp that can run balanced, or do I have this completely wrong. I have never run a balanced setup.
The one digital cable will go from your transports digital (output) to the DAC's digital (input). I don't think it really matters if you run balanced or unbalanced I/C's from DAC to preamp. But, I'm not sure from a technical aspect. Never really considered that. Interesting, I will have to research it.
Thanks...
Initial impressions on the transport...The weakest link in my audio setup is my speakers, a very old set of Energy C2's from the mid 90's. They are very musical from the mid range up but till now have exhibited no evidence of base. This new setup almost reverses that. All of a sudden I have lower midrange base. Actual punchy base (not vague rumbles)...never expected. The trade off seems to be with the treble. The speakers always gave me a very well defined treble, even with tubes. Now that seems to be muted...almost like going from push pull tube sound to triode.
I suspect the treble might be 'fixed' by using a real audio digital cable between the transport and the DAC. Today I am using a 1ft monster cable 'video' cable of undetermined cost and age, all that I have at the moment.
While I can ill afford to have an audio failure right now as they are always hits to the wallet, I am having a very good time playing..
On a related note...my towns record club (Boise's Vinyl Preservation Society) had its annual record sale on Sunday. Lots of dealers and lots of foot traffic. The local university PBS radio station donated its entire collection of records as a fund raiser and I had to organize maybe 500 records with poor jackets BUT, great actual records in amazing condition. At $1 each, I stocked up and have not played a clunker yet! So, my living room basic vinyl setup is getting as much play as my serious digital system. I have been playing more music over the last week then in a long time. So many records I am running out of record cleaner.
If something like that is a problem, then the cable is the wrong impedence, or the ends are improperly terminated. In this day and age when nobody seems to know analog electronics (well, except for some of the guys here who do things like tube amps) any more, who knows what's really set up.
The digital cable and the analog cable do not have to have the same kind of termination.
If your digital cable is balanced, and both the DAC and transport are balanced, that's good. If the analog out from the DAC is then unbalanced, standard RCA is likely your weapon of choice.
Now, if you're sending the digital signal two places, splitting it does create a problem.
70% Isopropyl alcohol and distilled water would be cheaper. Mix it 50/50 and you are good to go. That's what I did when I was into Vinyl. I should have my butt kicked for getting rid of all my audiophile pressings because the Transrotor turntables have me captivated at the moment